Radioactive product and method of producing the same



Patented May 22, 1951 RADIOACTIVE PRODUCT AND METHOD OF PRODUCING THESAME Louis B. Werner, Berkeley, Calif., assignor to the United States ofAmerica as represented by the United States Atomic Energy Commission NoDrawing. Application January 25, 1949, Serial No. 72,753

6 Claims.

The present invention relates to a radioactive product comprisingamericium impregnated on a suitable stable carrier, and to a method ofproducing the same.

One of the chief objects of the present invention is to provide aradioactive product containing americium.

Another object is to provide a process for separating americium fromcontaminants in a suitably conditioned aqueous solution by utilizing asuitable carrier material.

It is a still further object of the present invention to removeamericium from a solution by means of an added carrier of pentavalenttantalum, thereby forming a radioactive product consisting of americiuminterspersed with the tantalum carrier.

Other objects and advantages will be apparent from a consideration ofthe following description.

In general, the artificially produced radioactive element americium hasa five hundred year half-life and its specific alpha activity amounts to7.0 alpha disintegrations per minute per milligram. From a considerationof this property of americium it is evident that when handling thiselement, even in milligram amounts, special precautions and techniquesmust be developed and perfected in order to provide adequate protectionfor the operator.

Since in the art of americium chemistry one is dealing with extremelysmall amounts of material, it is readly apparent that these amounts maybe so small as to defy ordinary physical and chemical manipulations. Forexample, in the field of radiochemistry, some compounds are obtained inconcentrations 10 or more times as dilute as those concentrationsusually encountered in other fields of chemistry. Accordingly, at suchconcentrations, precipitation of insoluble compounds usually fails sincethe attainable initial concentrations of such compounds are less thanthose required for precipitation. In this connection, in addition to theall-important safety considerations which must be constantly observed,serious problems regarding adsorption of trace material on the Walls ofthe container are encountered. Moreover, the actual physicalmanipulations, such as filtering, transferring from one vessel toanother, and the like, necessitate the development of special techniquessubstantially dilierent from those normally used in the macro-chemicalfield.

From the foregoing, it is evident that conventional means and practicesare generally inadequate for removal of small amounts of this highlyradioactive element from solution while simultaneously forming asuitable radioactive product having the property of retaining thevaluable americium. I have now discovered that certain substances whenplaced in contact with trace amounts of radioactive americium have theability to cause the americium to become associated therewith by variousmechanisms which at present are not well understood. These substancesare generally termed carriers; 1. e., these substances carry theassociated trace amounts of americium along with them through variouschemical and physical operations during particular processes. It hasalso been found that the trace amounts of americium can be embodied withtheir carriers, and from this property it is possible by using such acarrier to increase the quantities involved so that standard chemicaland physical means may appropriately be employed to process theamericium.

In carrying out my invention, a solution of americium is treated with asuitable oxidizing agent in order to oxidize the americium to thepentavalent state. The solution is then heated to a temperature of from50 C. to 100 C. and to it is added a solution containing tantalum, alsoin the pentavalent state. Heating is continued and the tantalumprecipitates from solution. The resulting pentavalent tantalumprecipitate, probably a hydrated oxide, carries with it the pentavalentamericium. The precipitate comprising americium and its tantalum carrierare removed from the solution in any appropriate conventional manner,preferably by centrifuging the mixture. This precipitate comprises aseparate article of commerce which may serve as a means for storing,retaining, or handling americium, as an intermediate or as a productuseful for any purpose relying upon the intense radioactivity of theretained americium.

ExampZe.A 5 microliter portion of an aqueous americium solutioncontaining about 5 micrograms of pentavalent americium per milliliter isheated at deg. C. for five minutes. About 2 microliters of a 2.75 MK2003 solution of pentavalent tantalum containing '75 milligrams oftantalum per milliliter is added. The resulting solution is heated forat least one-half hour and then centrifuged. Alpha analysis ofapproximately 1 microliter portions indicate that about 20% of thepentavalent americium is carried.

The herein disclosed process for the manufacture of a. radioactiveproduct of americium should not be construed as being restricted tolaboratory investigations of americium merely because the phenomenon ofcarrying is associated with microscopic or trace amounts. On thecontrary, it is to be stressed that in industrial as well as researchprocesses involving the use of radioactive materials such as americium,the amounts involved are extremely small because of the great expenseand health hazard involved.

While the salient features of this invention have been described indetail with respect to one embodiment, it will, of course, be apparentthat numerous modifications may be made within the spirit and scope ofthis invention, and it is not therefore desired to limit the inventionto the exact details shown, except in so far as they may be defined inthe following claims.

What is claimed is: L

1. A radioactive product comprisin a hydrated pentavalent tantalum oxideprecipitate carrying americium values in which the amount of saidamericium is less than the amount of tantalum contained therein.

2. In a process for the production of a radioactive compositioncontaining tantalum and americium, the steps comprising mixing acarbonate solution of pentavalent tantalum ions with a solutioncontaining pentavalent americium ions, and heating said solution toprecipitate tantalum as a hydrated oxide thereby carrying americium fromthe solution.

3. In a process for the production of a radioactive product comprisingamericium values carried by a hydrated pentavalent tantalum oxide, thesteps comprising mixing a carbonate solution containing pentavalenttantalum. ions with a solution containing pentavalent americium ionswhile the latter solution is at a temperature in the range of about C.to 0., heating said solution to precipitate the tantalum ions as ahydrated oxide thereby carrying said americium ions from the solution,and separating the precipitate from said solution.

4. In a process for the production of a radioactive composition, thesteps comprising, mixing a heated solution containing pentavalentamericium ions with a carbonate solution containing pentavalent tatalumions, and precipitating said tantalum ions by heating said solutionthereby carrying americium as a hydrated oxide from said solution.

5. The radioactive product comprising pentavalent americium valuescarried by a hydrated pentavalent tantalum oxide precipitate.

6. In a process for the manufacture of a radioactive product, the stepscomprising mixing a heated solution containing about 5 micrograms permilliliter of pentavalent americium ions with an amount of a 2.75 Mpotassium carbonate solution containing about '75 milligrams permilliliter of pentavalent tantalum ions equivalent to about four-tenthsof its own volume, heating said mixed solutions for at least one halfhour to precipitate said pentavalent tantalum ions and thereby carrysaid americium ions from the solution, and separating the precipitatefrom said solution.

LOUIS B. WERNER.

No references cited.

1. A RADIOACTIVE PRODUCT COMPRISING A HYDRATED PENTAVALENT TANTALUMOXIDE PRECIPITATE CARRYING AMERICIUM VALUES IN WHICH THE AMOUNT OF SAIDAMERICIUM IS LESS THAN THE AMOUNT OF TANTALUM CONTAINED THEREIN.
 1. IN APROCESS FOR THE PRODUCTION OF A RADIOACTIVE COMPOSITION CONTAININGTANTALUM AND AMERICIUM, THE STEPS COMPRISING MIXING A CARBONATE SOLUTIONOF PENTAVALENT TANTALUM IONS WITH A SOLUTION CONTAINING PENTAVALENTAMERICIUM IONS, AND HEATING SAID SOLUTION TO PRECIPITATE TANTALUM AS AHYDRATED OXIDE THEREBY CARRYING AMERICIUM FROM THE SOLUTION.